This invention relates to light curing system and particularly relates to a light curing system for portable light curing devices used in dental applications.
Light cured composites have become materials of choice for a large number of dental restorations. These composites are easy to work with, contain no potentially dangerous metals, and are available in a large variety of shades to match the tooth enamel color of the patient. In use, the composite is first applied onto the area on the tooth of the patient and then it can be hardened or photo polymerized by exposing it to a high intensity light of wavelengths between 400 and 500 nanometers. Typically the high intensity light is provided by the light generated by a quartz halogen light source. The light is delivered to the composite at the patient's tooth by an elongated flexible light guide. Such elongated light guide often is awkward to manipulate and restricts the mobility of the dentist. In another curing light construction, the light lamp is incorporated in a hand-held unit which is connected by a power supply cord to a power supply for providing the electrical power for operating the light lamp. The elongated power supply cord in this case again restricts the mobility of the dentist.
Recently, attempts have been made to provide a battery powered portable hand-held light unit. The concept has been to free the dentist or assistant completely for better mobility when performing the light curing operation and to allow easy movement of the light from operatory to operatory. However, such portable curing units have been unsatisfactory, in that the curing light generated by the battery in the unit is not constant. Light cured composites used in dentistry vary in cure depths and speeds from manufacturer to manufacturer, from one shade of color to another and from one fill material to another. Cure times used by dentists as recommended by the composite manufacturers vary from ten seconds to one minute. If multiple restorations are being performed in a patient's mouth there can require up to 8 minutes or longer of light curing time. Undercuring is one of the major causes of restoration failures, and undercuring may lead to post operative sensitivity and/or marginal leakage which may lead to secondary carries. It is therefore an absolute necessity that a battery powered curing light unit should be capable of not only multiple exposures that may result in accumulations of up to 8 minutes or longer ON time, but the battery powered curing light unit must provide a consistent output that the dentist can count on. Only with a consistent light output in the wavelength range of between 400 and 500 nanometers can the dentist judge the curing time exposure required by the shade of the material being used in the restoration and the depth of the material being used in the restoration. In the known portable battery powered light curing device, the electrical power of the battery decreases rapidly with the length and number of ON time, and the intensity of the light output also proportionally decreases accordingly. Thus, the output light intensity is not consistent and is unreliable.